Beryllium product comprised of beryllium particles coated with a metal beryllide



United States Patent 3 Claims. (Cl. 29-1822) ABSTRACT OF THE DISCLGSURE Beryllium metal shapes formed from beryllium metal particles having metal coating thereon which form beryllides, when subjected to heat and pressure, around each particle and at the interface of each beryllium particle.

The beryllium particles are of a size from 4 to 74 microns, and the coating can be any metal such as chromium, copper, nickel, columbium, molybdenum, cobalt or This application is a divisional application of Ser. No. 465,167, filed June 1-8, 1965 now Patent No. 3,298,829.

This invention relates to high strength beryllium and processes of preparing the same.

More specifically, it deals with a process of preparing a beryllium metal having superior elastic modulus, high precision elastic limit, and high tensile strength.

It is an object of the present invention to set forth a new process for producing a beryllium metal having high strength.

Another object of the present invention is to produce a beryllium metal having superior elastic modulus, high precision elastic limit, and high tensile strength which will not experience grain growth during fabrication.

A further object of the instant invention is to set forth a process of producing high strength beryllium alloys wherein the alloy is characterized by a beryllide of the alloying metal at the interface between the particles, and surrounding each particle of beryllium powder so as to inhibit grain growth and reinforce the beryllium matrix.

A more specific object of the instant invention is to set forth a process whereby beryllium powder is coated with a thin coating of a metal which will form a beryllide when pressed into shape under heat.

Other objects and advantages of the invention will become more apparent from the following detailed description and examples.

It has been found that high strength beryllium metal can be formed without sacrificing low bulk density and at the same time having superior elastic modulus, high precision elastic limit, and high tensile strength by coating beryllium powder with a metal capable of forming a beryllide and subsequently hot-pressing the powders to form the new beryllium metal.

The beryllium powder used is of a size of about 4 to 74 microns, but preferably in the order of 4 to 15 microns. This powder is coated with a metal capable of forming a beryllide in any suitable manner, such as for example in the process disclosed in copending application Ser. No. 442,240, now filed Mar. 22, 1965, which is a continuation-in-part of application Ser. No. 260,857, now abandoned. In practice, coatings of up to 50 augstroms "have been found suitable This powder when subjected to pressure and heat forms a beryllide on the surface of each individual particle and at the interface between particles which inhibits grain growth and reinforces the beryllium matrix.

3,385,676 Patented May 28, 1968 Typical of the metals which form beryllides are chromium, copper, nickel, columbium, molybdenum, cobalt and iron. The pressure can vary from 350 pounds per square inch to 12000 pounds per square inch, and the tem- 5 perature for pressing may vary betwene :1900 F. to 2200 F. The pressure and temperature utilized as well as the duration of pressing may vary dependent upon the physical characteristics, such as size of the shape being produced.

Some typical examples illustrating the compositions, processes and characteristics of the beryllium metal are the following.

EXAMPLE I Nominal 11 micron beryllium powder was vacuum hotpressed at 2000 F. and 2000 p.s.i.

The chemistry of both the treated powder and the resultant pressing are:

By Analysis, percent Constituent Treated Powder Hot Pressed O. 5 4. 59 (X-ray diff.)

1 Balance.

Example I when hot-pressed and tested gave the following properties:

Test Direction U.T.S. .2% Y.S. Percent In. in. 2n. in. El. PEL PEL Nil Nil 22, 125 Nil Nil 2S1, 750 37, 700 Nil Nil 15, 000 43, 000 Nil Nil 19, 000 Nil Nil Nil Nil 1 Tested with extensometer, premature notch failure. Modulus equals 55.6 x 10" and 52.8 x 1() respectively.

2 Not determined due to gage slippage.

3 Tested without extensometel.

L=Longitudinal specimen.

T =Transverse specimen.

Some other examples showing beryllium metals in which the powders were coated with chromium are the following:

TABLE I.'IYPICAL CHEMISTRY OF Be-Or 5O Constituent Example No. Example No.

II III 268 438 113 127 027 034 095 L .001 015 L O01 210 235 027 039 NOTE.-L indicates less than.

1 Balance.

TABLE Ill-MECHANICAL PROPERTIES OF Be-Cr (AS PRESSED) Example I was subjected to solution annealing after pressing, and gave the following results.

TABLE IIL-PROPERTY RESPONSE OF EXAMPLE I TO SOLUTION ANNEALING TABLE IV.HARDNESS RESPONSE TO SOLUTION AN- NEALING-AIR COOLING Temper- Hardness RB Example I ature, F. Time Change Before After The following tests were made to show the superior strength of metal-coated beryllium powder over a typical surface-oxidized beryllium powder:

EXAMPLE V Composition A Nominal 11 micron beryllium powder was chromeq coated and vacuum hot-pressed at 2000 F. and 2000 p.s.i. yielding a density of 1.876 gr./cc. The powder and hotpressed chemistries were:

Constituent Powder, Hot-Pressed,

ereent percent 0. 5 4. 59 (X-ray diff.)

1 Balance.

Composition B Ball milled beryllium powder, surface oxidized to a minimum of 4.25% BeO and containing no alloy coating was vacuum hot-pressed at 2000 F. and 2000 p.s.i. yielding a density of 1.892 gr./cc. Weighted average powder particle size per Coulter counter was 8.2 microns. The powder chemistry was:

The above examples were tested and showed the following results:

TABLE V U.T.S. Y.S. Elongation, PEL p.s.i. p.s.i. percent p.s.i.

Composition A Nil 22,125 Composition l3 50, 700 0. 75 7, 500

TABLE VI Material Original Grain Size, Grain Size after microns 2,200 E, 2 hours Composition A 7 7 Composition B 9 13.3

Other data substantiating the inhibiting effect of the beryllide film is listed below for Composition A.

Hours at 2,175 E. Original Size Final Size Final in Mierons in Microns Hardiness, R

It appears that after sixteen hours, full solutioning of the beryllide occurs, as evidenced by the very slight change in hardness between 16 and 32 hours, and the beryllide has diffused into the beryllium matrix. Once the beryllide has diffused into the matrix, grain growth occurs. For example, note increase from 7.4 to 12.4 after 32 hours at 2175 F.

In view of the foregoing, it is apparent that there is provided a new and improved process for producing heattreatable beryllium metal of superior mechanical properties without sacrificing the weight advantage of beryllium. As set forth above, the process involves the coating of beryllium powders with a metal which will form a beryllide on the surface of each individual particle and at the interface of said particles when pressed under heat. This beryllide interface prevents grain growth of the beryllium metal, and reinforces the beryllium matrix by providing a beryllide network throughout the beryllium pressing, thus increasing the strength of the beryllium product.

This process provides a beryllium product with high strength, a high precision elastic limit, and a superior modulus of elasticity. The precision elastic limit relates to the dimensional stability of the metal and is equivalent to the amount of stress which will cause one millionth of inch permanent deformation.

As stated above, it is within the scope of this invention to utilize any metal for coating the powders which will form a beryllide on the surface of the powders when pressed.

As this invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, the present embodiment is therefore illustrative and not restrictive, and since the scope of the invention is defined by the appended claims, all changes that fall within the metes and bounds of the claims or that form their functional as well as conjointly cooperative equivalents are therefore intended to be embraced by those claims.

I claim:

1. A beryllium metal shape consisting essentially of bonded beryllium particles of a size of from 4 to 74 microns, each of said particles being coated with a beryllide of a metal selected from the group consisting of chromium, copper, nickel, columbium, molybdenum, cobalt and iron.

2. A beryllium metal shape as set forth in claim 1 wherein the particles are of a size of from 4 to 15 microns.

3. A beryllium metal shape as set forth in claim 1 wherein the beryllide coating has a thickness of up to 50 angstroms.

References Cited UNITED STATES PATENTS 3,294,530 12/1966 Storchheim 212X 3,150,975 9/1964 Beaver 752l4 FOREIGN PATENTS 522,463 6/1940 Great Britain. 527,618 10/1940 Great Britain.

CARL D. QUARFORTH, Primary Examiner. A. J. STEINER, Assistant Examiner. 

